UBC mine engineering professor Dirk Van Zyl (left) is introduced by Energy and Mines Minister Bill Bennett as one of three independent experts to investigate the cause of the Mount Polley tailings dam failure. Their report is due by Jan. 31.

Mount Polley spill may be left in place

Further tests will determine whether the metal-bearing sand will be removed or left where it is, Mines Minister Bill Bennett says

Further tests of mine tailings spilled down a creek bed from the Mount Polley mine will determine whether the metal-bearing sand will be removed or left where it is, Energy and Mines Minister Bill Bennett said this week.

The first lab tests on sediment samples at the mouth of Hazeltine Creek showed that while the material that poured down to the creek mouth in Quesnel Lake isn’t a health hazard to humans, its iron and copper content are above federal and provincial standards for aquatic life.

Bennett said it’s encouraging that the first sediment results did not show presence of arsenic, mercury or cadmium, toxic elements found in mine rock or used in mine processing.

A comparison sample of compact sediment from the mouth of nearby Raft Creek, not affected by the Aug. 4 tailings pond breach, also tested above sediment quality guidelines for iron. The environment ministry says mineral deposits that attract mine development often have naturally occurring metal concentrations much higher than other areas.

“What we need to do is test those sediments to determine whether it’s better environmentally to leave them there or to try to collect them and get them out of the creek bed and get them out of the creek mouth in Quesnel Lake,” Bennett said. “Before you start dredging lake bottoms and trying to clean up the bottom of a creek bed to get the sand out, you’ve got to determine what the risk is first, and that’s the phase that we’re in right now.”

There are two priority jobs underway on the spill site. One is pumping down the level of Polley Lake, the smaller lake next to the mine site that received a surge of water and tailings that plugged the outlet with an elevated water level. The other is reconstructing the breached section of the dam to prevent rain from carrying more tailings from the pond.

Interior Health is reviewing water and sediment sample results and a long-term monitoring and remediation plan has been submitted by the mine operator, a division of Imperial Metals.